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git-svn-id: file:///Users/olsen/Code/migration-svn-zu-git/logical-line-staging/clib2/trunk@14685 87f5fb63-7c3d-0410-a384-fd976d0f7a62
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Olaf Barthel
127
library/math_kernel_tan.c
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127
library/math_kernel_tan.c
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/*
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* $Id: math_kernel_tan.c,v 1.1.1.1 2004-07-26 16:30:48 obarthel Exp $
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*
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* :ts=4
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*
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* Portable ISO 'C' (1994) runtime library for the Amiga computer
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* Copyright (c) 2002-2004 by Olaf Barthel <olsen@sourcery.han.de>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Neither the name of Olaf Barthel nor the names of contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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*
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* PowerPC math library based in part on work by Sun Microsystems
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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*/
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#ifndef _MATH_HEADERS_H
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#include "math_headers.h"
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#endif /* _MATH_HEADERS_H */
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/****************************************************************************/
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#if defined(FLOATING_POINT_SUPPORT) && defined(PPC_FLOATING_POINT_SUPPORT)
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/****************************************************************************/
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static const double
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one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */
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pio4 = 7.85398163397448278999e-01, /* 0x3FE921FB, 0x54442D18 */
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pio4lo= 3.06161699786838301793e-17, /* 0x3C81A626, 0x33145C07 */
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T[] = {
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3.33333333333334091986e-01, /* 0x3FD55555, 0x55555563 */
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1.33333333333201242699e-01, /* 0x3FC11111, 0x1110FE7A */
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5.39682539762260521377e-02, /* 0x3FABA1BA, 0x1BB341FE */
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2.18694882948595424599e-02, /* 0x3F9664F4, 0x8406D637 */
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8.86323982359930005737e-03, /* 0x3F8226E3, 0xE96E8493 */
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3.59207910759131235356e-03, /* 0x3F6D6D22, 0xC9560328 */
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1.45620945432529025516e-03, /* 0x3F57DBC8, 0xFEE08315 */
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5.88041240820264096874e-04, /* 0x3F4344D8, 0xF2F26501 */
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2.46463134818469906812e-04, /* 0x3F3026F7, 0x1A8D1068 */
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7.81794442939557092300e-05, /* 0x3F147E88, 0xA03792A6 */
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7.14072491382608190305e-05, /* 0x3F12B80F, 0x32F0A7E9 */
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-1.85586374855275456654e-05, /* 0xBEF375CB, 0xDB605373 */
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2.59073051863633712884e-05, /* 0x3EFB2A70, 0x74BF7AD4 */
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};
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double __kernel_tan(double x, double y, int iy)
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{
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double z,r,v,w,s;
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int ix,hx;
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GET_HIGH_WORD(hx,x);
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ix = hx&0x7fffffff; /* high word of |x| */
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if(ix<0x3e300000) /* x < 2**-28 */
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{
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if((int)x==0) { /* generate inexact */
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unsigned int low;
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GET_LOW_WORD(low,x);
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if(((ix|low)|(iy+1))==0) return one/fabs(x);
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else return (iy==1)? x: -one/x;
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}
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}
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if(ix>=0x3FE59428) { /* |x|>=0.6744 */
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if(hx<0) {x = -x; y = -y;}
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z = pio4-x;
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w = pio4lo-y;
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x = z+w; y = 0.0;
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}
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z = x*x;
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w = z*z;
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/* Break x^5*(T[1]+x^2*T[2]+...) into
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* x^5(T[1]+x^4*T[3]+...+x^20*T[11]) +
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* x^5(x^2*(T[2]+x^4*T[4]+...+x^22*[T12]))
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*/
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r = T[1]+w*(T[3]+w*(T[5]+w*(T[7]+w*(T[9]+w*T[11]))));
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v = z*(T[2]+w*(T[4]+w*(T[6]+w*(T[8]+w*(T[10]+w*T[12])))));
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s = z*x;
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r = y + z*(s*(r+v)+y);
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r += T[0]*s;
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w = x+r;
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if(ix>=0x3FE59428) {
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v = (double)iy;
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return (double)(1-((hx>>30)&2))*(v-2.0*(x-(w*w/(w+v)-r)));
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}
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if(iy==1) return w;
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else { /* if allow error up to 2 ulp,
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simply return -1.0/(x+r) here */
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/* compute -1.0/(x+r) accurately */
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double a,t;
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z = w;
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SET_LOW_WORD(z,0);
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v = r-(z - x); /* z+v = r+x */
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t = a = -1.0/w; /* a = -1.0/w */
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SET_LOW_WORD(t,0);
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s = 1.0+t*z;
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return t+a*(s+t*v);
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}
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}
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/****************************************************************************/
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#endif /* FLOATING_POINT_SUPPORT && PPC_FLOATING_POINT_SUPPORT */
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